351w Help!! to Stroke or not to stroke?

Hey everybody,
I have a 81' stang with a 351w project I am in the middle of, I am working on getting 500bwhp, but the only phesable solution I have is to go 408 on it. I am trying to keep it in a reasonable budget as well. stats: roller 351w carb, gt40 heads, bbk headers, mild cam, c4 tranny w/ 2200 stall stage 2 kit, high rise intake,750 holley double pumper, fresh build on the whole motor. I am also doing all the nuts and bolts stuff myself, it will visit the track occasionally but will be mostly a street stang. I would look at getting a bigger stall, radiator, heads, etc. I also looked into the nitrous option, and have experience with it, but am not sure what the windsor can take. any idea's and suggestions would be much appreciated!! thank you very much.
 
To go 408 is gonna be an expensive project and could turn out to be a radical combo for the street. It really jus depends on ur budget and how often u want to drive the car on the streets. Im a fan of the bottle either way! :-)